B.Sc. II YEAR

CHORDATA

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Dr. R. JENNI & Dr. R. DHANAPAL DEPARTMENT OF ZOOLOGY M. R. GOVT. ARTS COLLEGE MANNARGUDI

CONTENTS CHORDATA COURSE CODE: 16SCCZO3

Block and Unit title

Block I (Primitive chordates) 1 Origin of chordates: Introduction and charterers of chordates. Classification of chordates up to order level. 2 Hemichordates: General characters and classification up to order level. Study of Balanoglossus and its affinities. 3 Urochordata: General characters and classification up to order level. Study of Herdmania and its affinities. 4 Cephalochordates: General characters and classification up to order level. Study of Branchiostoma (Amphioxus) and its affinities. 5 Cyclostomata (Agnatha) General characters and classification up to order level. Study of Petromyzon and its affinities. Block II (Lower chordates) 6 Fishes: General characters and classification up to order level. Types of scales and fins of fishes, Scoliodon as type study, migration and parental care in fishes.

7 Amphibians: General characters and classification up to order level, Rana tigrina as type study, parental care, neoteny and paedogenesis. 8 Reptilia: General characters and classification up to order level, extinct reptiles. Uromastix as type study. Identification of poisonous and non-poisonous snakes and biting mechanism of snakes.

9 Aves: General characters and classification up to order level. Study of Columba (Pigeon) and Characters of Archaeopteryx. Flight adaptations & bird migration.

10 Mammalia: General characters and classification up to order level, affinities of Prototheria, Metatheria and Eutheria. Study of rabbit (Oryctolagus) and dentition in mammals. Economic importance of mammals.

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REPTILIA

CONTENTS

Objective

Introduction

General characters of Reptiles

Classification up to order level

Extinct Reptiles

General study of Uromastyx

Poisonous and Non Poisonous Snakes

Identification of Poisonous Snakes

Identification of Non-Poisonous Snakes

Summary

Glossary

Terminal Question/Answer

References

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OBJECTIVE

D To understand the systematic and functional morphology of various groups of Reptilia. D To study their characters and classification upto order level. D To study a type of reptiles, Uromastyx. D To get knowledge about the identification of poisonous & non poisonous snakes.

INTRODUCTION

Reptilia is a group of tetra pod comprising today's turtles, crocodilians, snakes, amphisbaenians, lizards, tuatara, and their extinct relatives. The study of these traditional reptile groups, historically combined with that of modern amphibians, is called herpetology. Birds are also often included as a sub-group of reptiles by modern scientists.

The earliest known proto-reptiles originated around 312 million years ago during the Carboniferous period, having evolved from advanced reptiliomorph terapods that became increasingly adapted to life on dry land. Some early examples include the lizard-like Hylonomus and Casineria. In addition to the living reptiles, there are many diverse groups that are now extinct, in some cases due to mass extinction events. In particular, the K–Pg extinction wiped out the pterosaurs, plesiosaurs, ornithischians, and sauropods, as well as many species of theropods (e.g. tyrannosaurids and dromaeosaurids), crocodyliforms, and squamates (e.g. mosasaurids).

Modern reptiles inhabit every continent with the exception of Antarctica. Several living subgroups are recognized:

] Testudines (turtles, terrapins and tortoises): approximately 400 species ] Sphenodontia (tuatara from New Zealand): 1 species ] Squamata (lizards, snakes, and worm lizards): over 9,600 species

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] Crocodilia (crocodiles, gavials, caimans, and alligators): 25 species

Fig.8.1 Different type of Reptiles

Because some reptiles are more closely related to birds than they are to other reptiles (crocodiles are more closely related to birds than they are to lizards), many modern scientists prefer to make Reptilia a monophyletic grouping and so also include the birds, which today contain over 10,000 species.

Reptiles are tetrapod vertebrates, creatures that either have four limbs or, like snakes, are descended from four-limbed ancestors. Unlike amphibians, reptiles do not have an aquatic larval stage. Most reptiles are oviparous, although several species of squamates are viviparous, as were some extinct aquatic clades-the fetus develops within the mother, contained in a placenta rather than an eggshell. As amniotes, reptile eggs are surrounded by membranes for protection and transport, which adapt them to reproduction on dry land. Many of the viviparous species feed their fetuses through various forms of placenta analogous to those of mammals, with some providing initial care for their hatchlings. Extant reptiles range in size from a tiny gecko, Sphaerodactylusariasae, which can grow up to 17 mm (0.7 in) to the saltwater crocodile, Crocodylusporosus, which may reach 6 m (19.7 ft) in length and weigh over 1,000 kg (2,200 lb).

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GENERAL CHARACTERS

Reptiles are air-breathing vertebrate animals, a class to which lizards, crocodiles and snakes belong. It may be surprising for you to know that even the dinosaurs belong to the class reptilia. Reptiles can be easily identified with their special features like scaly integument. Class reptilia originated about 320-310 million years ago and underwent many changes to get adapted to the changing environment. Reptiles evolved from ‘reptile like amphibians’ and increasingly got adapted to terrestrial life. Reptiles are distributed across the planet except for Antarctica. They have higher level of intelligence as compared to birds. Some reptilian species, like the monitors, are also known to display complex behavior like cooperation. Some reptiles like snakes have toxic substances, generally termed venom, which are used as defense mechanisms and also to hunt their prey. These are fatal toxins and can even kill humans.

Morphological Characters

D The integument (skin) of reptiles is covered with epidermal scales. D Reptiles have a large bony plate called scutes. D Some reptiles like lizards, crocodiles, etc. have limbs whereas some species, like snakes, don’t. D Most of the reptilians have movable eye lids.

Physiological Characters

] Some species of lizards employ buccal pumping, a characteristic feature found in class amphibia. Buccal pumping is a respiratory method in which the animals move the floor of its mouth (buccal floor) in a rhythmic manner, thus allowing the respiratory gas to enter the lungs. ] Normally, oxygenated blood gets circulated all over the body and deoxygenated blood is carried back to heart. However, under specific conditions, deoxygenated blood can also be shunted to the body and oxygenated blood can be shunted back to lungs. ] Reptiles are not warm-blooded. They often depend on external sources of heat rather than regulating temperature by adjusting their metabolic rates.

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] The optimum body temperature varies according to the species. However, it is typically lesser than that of warm-blooded animals, except for American desert iguana, which has a body temperature of 35–40°C, thus reaching mammalian range. The body temperature of lizards, typical reptiles, ranges from 24–35°C. ] Reptiles have low resting metabolism which helps them spend less energy to sustain life activities and thereby enables them to conserve energy. ] Reptiles are unable to produce highly concentrated urine. This is because they lack Henle’s loop, a structure which is present in mammalian kidney. ] Reptiles use colon, part of their intestine, for the reabsorption of water. However, some reptiles can reabsorb water from the bladder also. They have nasal and lingual salt glands to excrete excess salt. ] Digestion is a slow process for reptiles. This is because of their lower resting metabolic rate and their inability to chew food. ] Reptiles are predominantly carnivorous, except for some herbivorous species like turtles. ] Lack of complex teeth lead to the inability to chew food and hence, some herbivorous reptiles swallow rocks and pebbles to aid churning of food. ] Most of the reptilians are adapted to see in daylight. They have a more advanced color vision than amphibians. However, in some species like the blind snake, vision is considerably reduced. ] Some snakes like pit vipers, boas and pythons have specialized visual organs (pits) that are sensitive to infrared radiations. These pits help them identify the presence of their warm-blooded prey like birds and mammals.

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Fig.8.2 Class Reptilia

CLASSIFICATION UP TO ORDER LEVEL

Key features of Class Reptilia

] Body varied in shape, covered with horny epidermal scales, sometimes with dermal plates; integument with few glands. ] Paired limbs, usually with five toes with claws, adapted for climbing, running or paddling; limbs absent in snakes and some lizards. ] Skeleton well ossified; ribs with sternum except in snakes, forming a complete thoracic basket; skull with single occipital condyle. ] Respiration by lungs. ] Three-chambered heart, except in crocodiles which have four-chambered heart. ] Metanephric kidney; uric acid is the main nitrogenous waste. ] Ectothermic animals.

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] Nervous system with primitive brain, spinal cord dominant. There are 12 pairs of cranial nerves. ] Sexes separate; fertilization internal, hemipenis as copulatory organ. ] Eggs covered with calcareous or leathery shells. Extra embryonic membranes, amnion, chorion, yolk sac and allantois are present during embryonic life.

Subclass IANAPSIDA

Anapsid reptiles are those in which the dermal bones form a complete roof over the skull, with no temporal fossae. Two main groups possess anapsid skull, the extinct Captorhinida and the extinct Chelonia.

Modern chelonians are classified into two suborders, according to the method of retracting the head into the shell. The most primitive group are the side-necked turtles (Suborder Pleurodira), which have very long necks to assist in catching fish. In these chelonians, the neck bends sideways in order to fit the head into the shell. Most modern species that belong to this group include the turtles, tortoises and terrapins.

Order chelonian

Tortoises and turtles do not have teeth but possess horny beaks. Tortoises are usually herbivorous while sea and fresh water turtles are omnivorous. Body is covered with a shell consisting of two parts – the dorsal carapace and the ventral plastron, which are connected by bridges between front and hind legs. The ribs and backbone are fused with the carapace.

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Fig.8.3 Subclass Ianapsida

Subclass II Parapsida

These are reptiles with one temporal fossa, placed high up on the skull. A number of different forms of aquatic reptile showed this form of skull, such as the Protosaurs, Nothosaurs and Placodonts but we will deal with the two largest groups – the ichthyosaurs and the plesiosaurs. These two lines of reptiles became modified for aquatic life in quite different ways but they share the same basic type of skull organisation, with minor differences. Both Ichthyosaurus and the Plesiosaurus became extinct at the end of the Cretaceous when many other terrestrial reptiles including dinosaurs died out.

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Subclass III Diapsida

These reptiles possess two temporal fossae in the skull and they have been the most successful and diverse of all the reptiles. They include the dinosaurs and pterosaurs which dominated the land and air during the Mesozoic era and also include the most successful of modern reptiles, such as the crocodiles, snakes and lizards.

The diapsid reptiles are divided into two major goups, the Archosauria and the Lepidosauria, which share the same type of temporal vacuities in the skull, but there are a number of differences in their skull construction which makes it possible that they may have evolved independently from separate cotylosaur ancestors.

Order Rhyncocephalia

The order contains only two species that live on some islands off the coast of New Zealand.They look like lizards but there are differences that set the tuatara apart from lizards. The tuatara spends daytimes in burrows. It comes out in the evening to feed on insects and other invertebrates.

Fig 8.4 Order Rhyncocephalia

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Order Squamata The order includes Lizards and snakes, which are creepers and inhabit a variety of habitats. Snakes are carnivorous but lizards eat a variety of foods including plants and insects. Snakes have descended from lizards and there are many similarities between them. Some characteristics that distinguish snakes from lizards are: ] Snakes do not have eyelids but lizards have. ] Snakes usually have one row of scales on the belly; lizards have many. ] Snakes do not have legs; most lizards have legs. ] Snakes have jaw bones that disarticulate allowing them to swallow large objects. Lizard jaw bones do not disarticulate.

Order Crocodilia: This order includes alligators, caimans, crocodiles and gharials that are found in and near water in warmer areas of the world. They eat fish, birds, turtles, and mammals. Members of the crocodile group have legs and feet designed for walking on land and a strong flattened tail used for swimming. The three groups are distinguished from one another by the shape of their heads. Alligators have a broad, rounded snout; while the crocodiles have a triangular head with a more pointed snout and gharials have a very long and narrow snout.

Fig 8.5 Crocodilia

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The Dinosaurs: Dinosaurs belonged to three orders:

D Order Saurischia - They possessed lizard-like pelvic girdle in which ischium and pubis bones diverge from the base. These dinosaurs were both bipedal and quadrupeds, carnivores as well as herbivores. Examples are, Allosaurus, Tyrannosaurus, Brontosaurus, Diplodocus, Brachiosaurus and Struthiomimus.

Fig 8.6 Order Saurischia

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D Order Ornithischia - They were dinosaurs with bird-like pelvic girdle in which both ischium and pubis are directed backwards. Examples include Iguanodon, Stegosaurus, Triceratops, Camptosaurus and Ankylosaurus.

D Order Pterosauria - They were flying reptiles in which forelimbs were modified to support a patagium that stretched from forelimbs to hind limbs. Their size varied from that of sparrow to giants that had wing span of 12 metres.

D Subclass IV Synapsida - These reptiles have one temporal fossa, on the lower side of the remporal region of the skull. They were the most successful and dominant reptiles during the Permian period. In the Mesozoic era they were largely replaced by other lines of reptiles such as dinosaurs, but the surviving synapsids gave rise to the mammals. There is a range of fossil species of these reptiles throughout the Mesozoic. At the start of the era they show typically reptilian characteristics but by the end of the era they became so mammal-like that it is difficult to know whether they should be classified as mammals or reptiles.

Fig 8.7 Animal of the subclass Synapsida

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EXTINCT REPTILES

The most famous members of the reptile family, the dinosaurs, became extinct as a result of the impact of a huge meteor, which changed the Earth’s environments, and as a result, many species could not survive. In the last few centuries however almost all known reptile extinctions can be attributed to human activity – either directly, through overhunting, or indirectly, by introducing predatory species, or altering the habitat the reptiles rely on for survival. Mariner’s often relied on reptiles (particularly tortoises) on strategic islands as a source of food, and in the nineteenth century in particular severely depleted some populations of reptiles, and completely wiped out others. Once we lose them, we will never get them back.

Below is a list of recorded extinctions of reptile species, with their locality, date of last sighting, and the reason for their disappearance. Human activity has been responsible in all known cases. There is also the Black Soft-shell Turtle (Aspideretes nigricans), which is extinct in the wild but can be found in a single artificial temple pond in Bangladesh.

Fig.8.8 Some of the Extinct Reptiles

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GENERAL STUDY OF UROMASTYX

Uromastyx is a genus of African and Asian agamidlizards, the member species of which are commonly called spiny-tailed lizards, uromastyces, mastigures, or dabb lizards. Lizards in the genus Uromastyx are primarily herbivorous, but occasionally eat insects, especially young lizards. They spend most of their waking hours basking in the sun, hiding in underground chambers at daytime or when danger appears. They tend to establish themselves in hilly, rocky areas with good shelter and accessible vegetation.

Taxonomy:

The generic name (Uromastyx) is derived from the Ancient Greek words ourá (οὐρά) meaning "tail" and mastix (meaning "whip" or "scourge", after the thick-spiked tail characteristic of all Uromastyx species. Species:

The following species are in the genus Uromastyx. Three additional species were formerly placed in this genus, but have been moved to their own genus, Saara.

Fig.8.9Uromastyx

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Description:

The size ranges from 25 cm (10 in) (U. macfadyeni) to 91 cm (36 in) or more (U. aegyptia). Hatchlings or neonates are usually no more than 7–10 cm (3–4 in) in length.Like many reptiles, these lizards' colors change according to the temperature; during cool weather they appear dull and dark but the colors become lighter in warm weather, especially when basking; the darker pigmentation allows their skin to absorb sunlight more effectively. Their spiked tail is muscular and heavy, and can be swung at an attacker with great velocity, usually accompanied by hissing and an open-mouthed display of (small) teeth.Uromastyxs generally sleep in their burrows with their tails closest to the opening, in order to thwart intruders.

Fig.8.10 Uromastyx macfadyeni

Distribution:

Uromastyx inhabit a range stretching through most of North and Northeast Africa, the Middle East, ranging as far east as Iran. Species found further east are now placed in the genus Saara.Uromastyxoccur at elevations from sea level to well over 900 m (3,000 ft). They are regularly eaten, and sold in produce markets, by local peoples. Uromastyx tend to bask in areas with surface temperatures of over 50 °C (120 °F)

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Reproduction –

A female Uromastyx can lay anywhere from 5 to 40 eggs, depending on age and species. Eggs are laid approximately 30 days following copulation with an incubation time of 70– 80 days. The neonates weigh 4–6 g (0.14–0.21 oz) and are about 5 cm (2 in) snout to vent length. They rapidly gain weight during the first few weeks following hatching. A field study in Algeria concluded that Moroccan spiny-tailed lizards add approximately 5 cm (2 in) of total growth each year until around the age of 8–9 years. Wild female uromastyx are smaller and less colorful than males. For example, U. (dispar) maliensis females are often light tan with black dorsal spots, while males are mostly bright yellow with mottled black markings. Females also tend to have shorter claws. In captivity female U. (dispar) maliensis tend to mimic males in color.Maliensis are, therefore, reputably difficult to breed in captivity. Diet-

These lizards acquire most of the water they need from the vegetation they ingest.Giving a Uromastyx a water bowl can lead to higher humidity in the cage and can cause problems for the animal.

Captivity –

Egyptian spiny-tailed lizard (Uromastyxa egyptia)

Historically, captive Uromastyx had a poor survival rate, due to a lack of understanding of their dietary and environmental needs. In recent years, knowledge has significantly increased and appropriate diet and care has led to survival rates and longevity approaching and perhaps surpassing those in the wild. The Mali Uromastyx (Uromastyx (dispar) maliensis) is considered an ideal species to choose as a pet because they readily adapt to a captive environment. Another species of Uromastyx that adapts to captivity well, and comes in "red" and "yellow", is Uromastyxgeyri, commonly called the Saharan Uromastyx. The red version is marketed as a red Niger Uromastyx but the yellow version is marketed as a yellow Niger Uromastyx. Proper enclosures can be costly, as these are roaming animals with large

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space needs for their size, combined with the need to provide heat and ultraviolet light. Though the lizards bask at very high temperatures, there must be a temperature gradient within the enclosure allowing them to cool off away from the heat lamps. A cooling- down period over winter months can trigger the breeding response when temperatures rise in the spring. The temporary slowing-down of their metabolisms also lengthens the animals' lifespans.

Fig 8.11 Egyptian spiny-tailed lizard (Uromastyxa egyptia)

Uromastyx are burrowing lizards, and need substrate deep enough to burrow in, or a low structure under which to hide. In the wild, these lizards' burrows can reach 3 m (10 ft) in length.

Nutrition - Captive uromastyxs’ diets should be largely herbivorous, consisting primarily of endive, dandelion greens, bokchoy, escarole, and most ground growing vegetables with little to no sugar, or of course an appropriate type of store-bought vegetarian lizard food. Some lettuces have almost no nutritive value. The lighter, whiter lettuce is not as nutritionally effective as the darker green lettuce. It is very important to avoid spinach, chard and flowering kale in the diets of all reptiles,. The lizards' food can be dusted with

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calcium and a uromastyx designed supplement to help prevent health problems. While young uromastix, like young iguanas, do eat some insects in order to gain access to the added nutrients while they are rapidly growing, the high levels of protein may cause liver damage in adults. These animals are primarily herbivores, as stated above, and so it's generally felt that they should only be fed plant matter. In the wild, adult Malis have been reported to eat insects at certain times of the year, when it is hot and their only food source available would be insects.

POISONOUS AND NON POISONOUS SNAKES

IDENTIFICATION OF POISONOUS SNAKES

Most of the snakes are non-poisonous. Identification of poisonous or non-poisonous snakes is important because sometimes the bite of a non-poisonous snake may lead to `death out of fear. The poisonous snakes possess certain characteristics by which it is possible to distinguish them from non-poisonous snakes. The poisonous snakes are identified by a careful examination of the following points.

I. Nature of the Tail -The tail of a snake should be observed first. If the tail of a snake is flat, laterally compressed and oar-shaped (adaptation to swimming in water), it is a sea snake. All sea snakes are poisonous. The body is covered by small scales dorsally. Ex: Hydrophis, Enhydrina. If the tail ends bluntly, it is non-poisonous. If the tail is round orcylindrical and pointed, it may be poisonous or non-poisonous. It may be terrestrial or fresh water.

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i. ii. iii.

Fig 8.12 Identification of Poisonous & Non Poisonous snake (Nature of tail)

II:Nature of The Ventrals-

If the tail is round and not compressed, then examine the ventrals (scales on the ventral side of the trunk).

D If the ventrals are small and narrow, it is a non-poisonous snake.

D In some non-poisonous snakes like Python, the ventrals are fairly broaa, but do not extend compieiely across the belly. On either side of ventrals, small scales are present.If the ventrals are broad extending completely across the belly, it may be poisonous or a non-poisonous snake.

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Fig. 8.13 Identification of Poisonous & Non Poisonous snake (Nature of ventral)

iv: Nature of the Scales On The Head :-

If the tail is round and the ventrals are broad, then examine the head of the snake. D If the head is triangular and covered with small scales and not with shields, it is a viper. All vipers are poisonous. Vipers are of two L types. 1. Pit vipers, 2. Pitless vipers. D If there is a loreal pit between the eye and nostril, the snake is a pit viper (pit organ is athermoreceptor) D Eg: Trimeresurus (lachesis) D Some pit vipers possess shields on their heads. Eg :Ancistrodon D If there is no loreal pit between the eye and the nostril, it is a pitless viper

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D D D

Fig 8.14 Identification of Poisonous & Non Poisonous snake (Nature of scale on the head) .

D If the head is covered with small scales and there is no loreal pit, then the sub- caudals are to be examined. D If sub-caudals are in two rows and there is no loreal pit, then the snake is Russels viper. D It is a pitiess viper with aiarge body and bears 3 rows of large diamond-shaped spots on the dorsal side of the body. D If the sub caudals are in a single row and there is no ioreai pit, then the snake is Echiscarinata(the little Indian viper). The head bears arrow shaped mark on the head. It is phoorsa

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Fig 8.15 Scale on body

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v. From the Nature of the Vertebrals -

D If the head is covered with shields, not with small scales it may be poisonous or non poisonous. Then examine the vertebrals (scales present along the mid-dorsal line on the back). D If the vertebrals are large and hexagonal, it is a krait and it is highly poisonous. In addition to the enlarged vertebrals, the krait is characterized by the presence of only 4 infra-labials of which the fourth one is the largest (infra-labials are the shields forming the margin of the lower jaw). The sub-caudals are present in a single row in krait. Eg; Bungarus.

D If the vertebrals are not large, then examine the supra-labial shields (the shields forming the margin of the upper jaw). If the third supra-labial shield touches the nasal shield and the eye, it is either a cobra or a coral snake. Both cobras and coral snakes are poisonous.

Cobras (Naja naja, Naja hanna) are identified by a hood and the coral snakes (C allophis, Hemibungarus) are identified by the presence of brilliantly coloured peculiar spots on the belly and by the absence of hood.

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Fig 8.16 Snake Bite

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Vi: From the Nature of Snake Bite: Depending on the nature of bite, it can be judged whether it is a poisonous or non- poisonous snake. When a poisonous snake bites, there will be 1 or 2 punctures on the skin of the victim (the punctures are made by fangs). If a non-poisonous snake bites, many punctures are usually made on the skin by the maxillary teeth of upper jaw.

IDENTIFICATION OF NON-POISONOUS SNAKES

D Non-Venomous Snakes : There are no universal distinguishing features that separate venomous from non- venomous snakes. People must learn to identify the dangerous species of snakes in their areas or the areas they plan on visiting.

Non-venomous snakes have teeth, just like the venomous variety. So even in the case of a bite from a non-venomous snake, care should be given to watch for infections, as with any small injury. Bites from large non-venomous snakes can also be devastating - some large python and boas are able to cause massive lacerations requiring urgent medical care.

Fig 8.17 Venomous pit viper v/s non venomous snake

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D Advice :

It’s best to leave all snakes alone, just like any wildlife. They have their place in nature and would certainly prefer to leave us alone as well.

D How They Kill

Many non-venomous snakes constrict their prey. Constriction is not a bone breaking experience like we often see in the movies. A snake will strike out to bite its prey, throw a couple of coils around it and begin to squeeze. Two things generally happen: every time the animal (prey) exhales, the snake will squeeze tighter. Eventually, the animal will not be able to inhale. However, there is so much power behind the coils that most animals typically die from heart failure because so much pressure is being applied to the chest cavity that the heart doesn’t have any room to continue beating. Death is very rapid, and in most cases takes less than a minute.

D Defenses

All snakes possess teeth that can be used in defensive bites. Most snakes rely on camouflage to avoid being seen, others coil up in a tight ball with the head in the middle, some rattle the tail, and a few rub their scales together to produce a rasping “leave me alone” sound, but almost all will flee if given even the slightest opportunity.

Non-Venomous Snakes: Most of the world’s snakes are what are referred to as clinically non-venomous. This means they do not produce a toxin that is clinically significant to people. However, many harmless-to-humans snakes, like Hognose snakes, Garter snakes and Rat snakes for example, do produce toxins that are scientifically or technically venomous. Boas, pythons, bull snakes and king snakes are examples of truly non-venomous snake species.

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BITING MECHANISM OF SNAKES:

The mechanism of biting is a complicated process and it can be described in the following three steps.

(a) Opening of the mouth: By the contraction of digastric muscles the mouth is opened. (b) Rotation of maxilla: As the mouth opens the lower jaw moves forward and a rotation of the squamosal, quadrate and mandible in relation to each other occurs. Now the sphenoptery goid muscles contract. This contraction results in the forward movement of ptery goid and up-pushing of the ectoptery goid. The upward movement of the ectopterygoid brings about a rotation of maxilla on its own axis round the lacrymal and as a result the fang is raised and becomes directed forward. The fang is nearly horizontal in position when the mouth remains closed. But during opening of the mouth to bite, the fang assumes almost vertical position.

Fig 8.18 Biting apparatus in snake

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(c) Closing of mouth: The closing of the mouth is brought about by the contraction of the temporalis and sphenopterygoid muscles. The point of fang is directed back ward while the mouth is closed. It takes longer time to open the mouth than to close it.

(d) Toxicity of Snake Bite The snake poison or snake venom is useful in killing the prey and in defense. The poison is a pale yellow colored fluid made up of a mixture of two major types of powerful enzymes. They are Neurotoxin: It affects the central nervous system; especially the motor nerves and causes cardiac and respiratory failure. It is present in the poison of cobra (cobradin), Kraits, sea snakes etc. (except vipers). Haemotoxin: It includes cardio toxins and Haemorrhagins. It is present in the poison of vipers (viperidin). D Cardiotoxins: Affects the heart’ D Haemorrhagins: It affects cardiovascular system. They contain enzymes like proteolysins, lecithinases, phosphoridases etc. Proteolysinsand Lecithinasesdestroy the endothelium of blood vessels and cause profuse bleeding. D Phosphoridasesproduce haemolysis leading to cardiac and D Circulatory failures. i. Blood clotting results in thrombosis ii. Cardiac and respiratory failures iii. Clotting power of the blood is reduced, which results in profuse bleeding. iv. Blood corpuscles, linings of the blood – vessels and other tissues are destroyed. v. Due to the presence of hyaluronidasein the venom there is a rapid spreading of venom.

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Treatment of Snake Bite:-

First of all it must be confirmed whether the snake, which had bitten man, was in fact poisonous. A person bitten by any type of snake should by psychologically treated as it has been reported that, sometimes, due to the fear only the heart – failure results and man dies, even though bitten by a non- poisonous snake. If a man is bitten by a poisonous snake the following first aid and treatment are prescribed: (i) Immediately send for a doctor and do not disturb the patient. (ii) Undue excitement and exertion should be avoided. (iii) If bitten on a limb, a tourniquet should be applied between the wound and the heart. This constriction should be either of rubber tubing or of handkerchief etc. The constrictions should be kept only for 20 minutes and then release J for one minute until the skin becomes pink and is again tigmened. (iv) After applying the constriction, make an incision about 2 cm. deep into the bitten area and keep ice on it. Suction of the venom may be done by a suction cup and not by mouth. (v) Do not apply potassium permanganate to the wound, as it is a tissue poison. Very recently, its use has been objected to. (vi) Keep the patient warm and absolutely at rest. (vii) Alcoholic beverages should never be given. (viii) Give hot coffee, tea or milk, if possible.

SUMMARY

Most small children can tell you that ‘reptiles’ are the snakes, lizards, crocodiles, and turtles (perhaps with the dinosaurs thrown in) — suggesting that it’s easy to tell the difference between reptiles and other animals. Unfortunately, evolutionary biologists struggle with the same task, because phylogenetic analysis tells us loud and clear that these different types of what we loosely call ‘reptiles’ are not particularly closely related to each other ( Figure 1 ). On the evolutionary tree, some of them (dinosaurs, crocodiles) are much more closely related to birds than to the other animals that we call reptiles. Other reptiles are the descendants of very ancient lineages; for example, turtles separated from the other reptiles, including the now-dominant Squamata (lizards and snakes), at least 200 million years ago. And

CHORDATA 16SCCZO3 another 200-million-year-old lineage has left just a single survivor, a lizard-like creature (the tuatara), on a few islands in New Zealand.

GLOSSARY

Aestivate The behavior of laying dormant in the Summer to avoid heat or drought Albinism A genetic condition that manifests as a lack of pigment Allochthonus Not native Amelanistic Lacking in dark pigment

Anerythristic Lacking in red pigment Antivenin The medicinal treatment for envenomation Basking Laying in the direct rays of the sun for thermoregulatory or theraputic reasons Binomial A scientific name consisting of two parts, a genus and a species Biota The living organisms in a given area Carapace The dorsal portion of a turtle shell Carnivorous Meat eating Chelonian A turtle or tortoise Cloaca The common cavity and orofice where digestive, urinary and reproductive products are passed. Colubrid Snakes belonging to the taxonomic family Colubridae. Crepuscular Describes the behavior of being active during twighlight hours(dusk or dawn) Crocodilian A corcodile, alligator, caiman, or gahrial. Crotalin Snakes belonging to the taxonomic family Viperidae, but of the sub- family Crotalinae. These are the pit-vipers. Cryptic Describes the behavior of remaining hidden Cytotoxin A chemical toxin that acts directly on the body tissue. It is the most physically destructive component of snake venom.

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SELF-ASSESSMENT QUESTION

Multiple choice questions:

1. Lateral undulation is used by snakes in: (a) Serpentine locomotion (b) Forword locomotion (c) Locomotion in burrows (d) Locomotion in sand

2. The poison glands of snake are really a) Labial glands b) Tear glands c) Salivery glands d) Sebaceous glands.

3. A flying lizard is a) Chameleon b) Draco c) Neurotoxic d) None of these.

4. The Venom of snake is a) Haemolytic b) Neurotoxic & Homotoxic. c) Neurotoxic. d) None of these.

5. The study of reptiles is known as: (a) Herpetology (b) Ornithology (c) Icthyology (d) Osteology

6. In case of snake bite the best medicine to inject is a) Antivein b) Penicillin. c) Antibiotics d) Streptomycin.

7. Which is not true for COBRA? (a) A= Altered (b) CO= Spinal cord (c) BRA =Brain (d) COB= Coagulation of blood

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Answers

1(a) 2 (a) 3 (b) 4 (b) 5 (a) 6 (a) 7 (a)

TERMINAL QUESTIONS/ANSWER

Q 1 - Give the classification of reptilia?

Q 2 - Give the general characters of the reptilia?

Q 3- Describe the Biting Mechanism of snakes?

Q4 - Classify Poisonous and Non Poisonous Snakes?

Q5. Comment with suitable example. 1. Harpetology 2. Serpentology 3. Living fossils 4. Antivenin

Q 6. Write short notes on habit, habitat, and distribution of 1. Chelone. 2. Draco. 3. Chameleon 4. Cobra

REFERENCES

D Jordan E.L. and P.S. Verma 1995.Chordate Zoology and Elements of Animal Physiology.S.Chand and Co.New Delhi. D Kotpal, R.L 2012.Vertebrata, Rastogi publication Merruth. D Nigam,H.C.1983.Zoology of chordates,Vishal publication,Jalandhar. D Some figure and tax material are adopted from Wikipedia. D Some figure and tax material are adopted from Biozoom.

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UNIT: 9 AVES

CONTENTS

Objective

Introduction

- General characteristics of Aves

Classification

- General study of Columba (Pigeon).

- Characters of Archaeopteryx.

- Flight adaptations bird migration

- Summary

- Glossary

Terminal Question Answers

-References

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OBJECTIVE

a) To understand the systematics and functional morphology of various groups of Aves. b) To study the general characters and classification of Aves. c) To mak a general study of Columba (Pigeon). d) To study of characters of Archaeopteryx. e) To study the flight adaptations and bird migration.

INTRODUCTION

Birds (Aves) are a group of endothermic vertebrates, characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four- chambered heart, and a light weight but strong skeleton. Birds live world wide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) Ostrich. They rank as the class of tetra pods with the most living species, at approximately ten thousand, with more than half of these being passerines, sometimes known as perching birds or, less accurately, as song birds.

The fossil record indicates that birds are the last surviving group of dinosaurs, having evolved from feathered ancestors within the theropoda group of saurischian dinosaurs. True birds first appeared during the Cretaceousperiod, around 100 million years ago. DNA based evidence finds that birds diversified dramatically around the time of the Cretaceous–Paleogene extinction event that killed off all other dinosaurs. Birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling.Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails.

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Fig 9.1Different kind of Endothermic vertebrates

Birds have wings which are more or less developed depending on the species; the only known groups without wings are the extinct moss and elephant birds. Wings, which evolved from forelimbs, give most birds the ability to fly, although further speciation has led to some flightless birds, including ratites, penguins, and diverse endemic island species of birds. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly the aforementioned flightless penguins, and also members of the duck family, have also evolved for swimming. Birds, specifically Darwin's finches, played an important part in the inception of Darwin's theory of evolution by natural selection.

Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviors as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but

CHORDATA 16SCCZO3 rarely for life. Other species have polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Birds produce offspring by laying eggs which are fertilized through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Some birds, such as hens, lay eggs even when not fertilized, though unfertilized eggs do not produce offspring. Many species of birds are economically important. Domesticated and undomesticated birds (poultry and game) are important sources of eggs, meat, and feathers. Songbirds, parrots, and other

Fig 9.2 Different species of Birds (economically important, domesticated & undomesticated species)

CHORDATA 16SCCZO3 species are popular as pets.Guano (bird excrement) is harvested for use as a fertilizer. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational bird watching is an important part of the ecotourism industry.

GENERAL CHARACTERISTICS OF AVES

Major characteristics of birds:-

Birds compose a diverse class (Aves) of species, as dissimilar as tiny darting humming birds and 8-foot flightless ostriches, with about 9,000 living species known. Generally accepted to have evolved from reptilian dinosaurs, birds share several characteristics with other classes of animals, including a skeletal backbone housing a spinal cord, a four-chambered heart and warmbloodedness. Other of birds' characteristics are unique or essentially unique.

Feathers:-

Feathers are the defining characteristic of Aves, found on every living species of bird and no other class of animal. Feathers are made of keratin, the same substance that forms hair and nails in other animals and are highly modified scales. Feathers are critical not only for flight but also for warmth and protection against the elements -- and in many species, for males to attract mates. Soft, fluffy downy feathers help keep birds warm, contour feathers streamline birds’ bodies and aid in flying, and flight feathers on wings and tail give the bird loft. Birds shed, or molt, old feathers once or twice each year, depending on the species.

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Fig 9.3 Feather of Birds

Wings

All birds have wings, although not all birds fly. Nor are wings confined to Aves; bats are flying mammals and most insects have wings. Birds' bodies are beautifully designed for flight, with strong chest muscles and just enough curves to their wings to provide lift. Differences in wing shape provide different advantages to the various bird species.

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Fig 9.4 Wings of Birds

The narrow, sharp-tipped wings of the falcon provide speed; albatrosses soar high on wings much longer than they are wide. Most songbirds have elliptical, evenly shaped wings that facilitate quick, small movements in the tight spaces of their tree homes. Swimming birds, such as penguins and puffins, have flipper-shaped wings that propel them rapidly and gracefully through water.

Beaks:-

All birds have beaks, or bills, made of a bony core surrounded by a thin layer of keratin. Birds do not have true teeth, but many species have tomia -sharp ridges along the edges of their beaks. Birds do not chew food but grind or rip it into pieces small enough to swallow.

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Fig 9.5 Different kind of beaks in Birds The shape of a bird's beak indicates the bird's general diet. Meat-eaters like hawks and owls have sharp, hooked beaks for ripping and tearing. Strong, cone-shaped beaks help seed eaters break through shells. Ducks and geese have broad, flat beaks for straining food out of the water.

Eggs:-

All birds lay eggs, some very colorful or covered with spots. Eggs are not unique to birds, of course, as fish, reptiles, amphibians and insects also lay eggs. A bird egg has a hard shell made mostly of calcium and a layer of hardened mucus. Inside the egg, the developing embryo receives nutrition from the yolk and the albumin, the egg white. Most birds construct nests to protect their eggs, and then care for the eggs and the hatchlings. The majority of bird species are devoted parents; in most cases, both male and female care for young.

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Fig 9.6 Different kind of Eggs in Birds Skeleton

Most birds have lightweight skeletons with hollow bones. This keeps them light enough for flight. Many fused bones, including the collarbones or wishbones, make birds’ skeletons rigid in comparison to mammals'. This helps brace the birds' wings during flight. Their sternums, or breastbones, are large, providing sturdy attachment points for powerful wing muscles. Flightless penguins have heavy bones filled with marrow, helping them to survive in their freezing home range. Ostriches have heavy, solid bones in their legs, helping the birds run and defend themselves with powerful kicks.

CLASSIFICATION

Based on characters, Aves Class is divided into two sub-classes. Sub class: i) Archeornithes and Subclass ii) Neornithes

Subclass Archeornithes:

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1 In this subclass extinct birds are included. Those birds were alive in Mesozoic era. 2 These show a long tail with 13 or more than 13 caudal vertebrae. Pygostyle is absent. 3 Meta carpals are free. The free fingers of fore limb will end with claws. Eg: Archeopteryx, Archeormis

Fig 9.6 Example of Subclass Archeornithes Subclass Neornithes: 1. This subclass includes both extant and extinct birds. 2. Tail ends in pygostyle. The rectrices are arranged r a semicircular aroundpygostyle. 3. Teeth are absent in many forms. 4. Sternum is well developed. It shows a keel to which flight muscles are attached. 5. This subclass is divided into 4 super orders. 6. This subclass is divided into 4 super orders.

Neornithes 1. Odontognathae 2. Palaeognathe 3. Impennae 4. Neognathae

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Super order - Palaeognathae. 1 These are flightless birds. 2 They are more in numbers. 3 Wings are reduced or absent. 4 Teeth are absent. 5 Caudal vertebrae are free. This super order is divisible into 7 orders. Fig 9.7 Flightless Birds

Order (1) Struthioniformes: Ex, Struthiocamelus (Two toed African Ostrich (or) Ostrich) 1 Large flight-less bird. 2 Feathers are less. 3 They show two toed hind limbs. 4 Sternum is without keel. 5 Neck is very long and flexible. 6 Pygostyle is absent. 7 These birds are good runners. Fig 9.8 Example of Struthioniformes

Order (2) Rheiforms :- Rhea americana. (three toed (or) Ameri¬can ostrich).

1 This includes flightless, terrestrial bird. 2 They are good runners. 3 Wings are better developed. 4 The body shows more feathers. 5 The hind limb bea three toes. 6 Sternum is without keel.

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Fig 9.8 Example of Rheiforms

Order (3) Casuariformes. Ex: Casuarius (Cassowaries) Dromaeus (Emu) 1 These are flightless terrestrial birds. . 2 Head shows few feathers. 3 Neck and body show more feathers. 4 Wings are Rudimentus. 5 The hind limb shows three toes. Fig 9.9 Example of Casuarius

Order (4) Aepyomithiformes : Aepyornis. 1 These are extinct elephant birds. 2 Wings are vestigeal. 3 Legs are powerful. Hindlimbs show 4 toes. 4 Sternum is broad. Keel is absent. 5 Eggs are very big.

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Order (5) Dinomithiformes: Ex : Dinornis (Extinct) (Moas) 1 These are gaint flightless extinct birds. 2 Wings are absent. 3 Eggs ar e massive.

4 Sternum is reduced without keel.

5 Pectoral girdle is absent. Fig 9.10 Dinornis Order (6)Apternygiformes Ex : Apteryx (Kiwi). Newzeland bird 1. Thes eare flightless, terrestrial birds. 2. Wings are rudimentary. 3. Eyes are small. 4. Neck and legs vet small. 5. Hind limbs bear 4 toes. 6. Thes eare Nocturnal. They feed on inserts. 7. Eggs are largest relatively. 8. These are present only in Newzeland and Australia. Fig 9.11 Apteryx (Kiwi)

Order(7)Tinamiformes Ex :Tinamus. 1 These are small, terrestrial with little power of flight. 2 Wings are short and round. 3 Pygostyle is reduced. 4 Eggs are big.

5 They e at plant products.

Fig 9.12Tinamus

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Super Order Impennae:- This super order includes flightless aquatic birds. 1. Their foreKmbs are modified into paddles. This super order includes only one order.

Order Sphenisciformes (SPHENISCI FORMES) Ex: Aptenodyts (Penguin) 1. These are flightless aquatic birds. 2. Feathers are small scale like. They Cover the. Entire body. 3. Forelimbs are modified into paddles. And They are useful for swimming 4. Limbs are 4 toes. 5. Below the skin thick layer of fat will be present. Fig 9.13Aptenodyts (Penguin)

Super order: Neognathae: 1 This sub order includes modern flying birds. 2 Teeth are absent. – 3 Wings are well developed. 4 Sternum shows keel. 5 Flight muscles are well devebped. 6 Pygostyle is present. This super order is divisible into the following orders. Fig 9.14Example of Super order: Neognathae

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Order 1 :Gaviformea

Ex : Gaviaimmer (Common loon) 1 These birds show powerful fight 2 Toes are webbed.

Fig 9.15 Common loon

Order 2 :Podlcipit formes : Ex :Podiceps. 1 These are fresh water birds. 2 Feet are lobed.

Fig 9.16 Podiceps

Order 3 :Procellariiformes : Ex : Puffinus (Petrels, Diomedia ) ( Wandering albatross) 1 Skull shows large nasal gland. 2 Feathers are compact. 3 Wings are long and narrow.

Fig 9.17 Puffinus

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Order4 :Pelecaniformee

Ex : Pelecanus (Pelecan)

1 Aquatic fish eating birds.

2 Four toes are webbed.

Order5 :Clconiformee :

Ex: Ardea (great blue heron)

1 Neck is long and Legs are long,

2 Web is absent.

Order6 :Ariseriformea : Ex : Anserdomesticus (Duck), Cygnus (swan) 1 Beak is broad. 2 Tongue is fleshy. 3 Legs are short. 4Feet are webbed.

Fig 9.18 Duck

Order 7 : FaiconlformeA: Ex : Mihmsmigrans (Kite). Pseudogyps (Vulture) 1 Beak is short and curved. 2 Feet show curved daws. 3 They are strong fleers.

Fig 9.19 Vulture

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Order 8 : Galliforroea :

Ex GaOus (Jungle owl), Pavocristatus (Peacock) 1 Beak is short. 2 Terrestrial birds. 3 They will fly.

Order 9: Gruiformes : Ex Grus (crane) 1 They are small or medium large-size birds. 2 They may be weak or strong fliers. 3 Legs are long.

Fig 9.20 Grus (crane)

Order 10 Diatrymiformee;

1 These are extinct birds.

Order 11: - Chardriiforrae Ex:Larus (Gull) 1. Shore dwelling aquatic birds. 2. Toes are webbed.

Order 12 : Columbiformes :

Ex : 1. Columba livia (Pigeon) 2. Sterptopelia (Dove) 1 Skin thick and soft. 2 Beak is usually short and slender. 3 Crop produces pigeon milk to feed the young ones.

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Order 13 :Cuculiformee : Ex : .1. Cuculus (cuckoo) 2. Eudynamis (Koel)

1 Many Cuckoos are parasites. 2 The females lay their eggs in the nests of other birds. 3 The toes are four in number. 4 Tail is long.

Fig 9.21 Koel Order 14: Paitiaciforme : Ex : Psittaculaeupatra (Parra keet) 1 Feathers are green, blue, yellow. 2 Beak is short and curved. 3 Frugivorus forms.

Order 15: Strlgiformes :

Ex : Bubo bubo (green horned owl) 1 Head is large and narrow. 2 Retina contains many rods. Hence it can

see in the night time. 3 They are nocturnal predators.

Fig 9.22 Green horned owl

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Order 16: Caprimulgiformee:

Ex: Caprinulgus (Night jar) 1 Legs are weak. 2 Beak is small.

Fig 9.23 Night jar

Order 17 :Apodiformes :

Ex : Swift (Humming bird) 1 These are small birds. 2 They are powerful fliers.

Fig 9.24 Swift (Humming bird)

Order 18 :Coliifbrmee :

Ex : Cobus (Mouse bird) 1 Small birds. 2 Tail is long.

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Order 19 :Coraciformes : Ex : Akedo king fisher and hornbill 1 Beak is strong. It is useful to catch fishes. 2 Third and Fourth toes are fused at the base.

Fig 9.25Akedo king fisher and hornbill

Order 20 :PiciformeP : Ex : Brachypternus (Wood pecker) 1 Dino pium (Wood pecker) 2 Tail feathers are pointed.

Order 21 : Passed formes :

1 Passer domesticus (Sparrow) 2 Corvus (Crow) 3 Acridotherus (Myna)

Fig 9.26 Sparrow

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9.4. GENERAL STUDY OF COLUMBA (PIGEON)

Systamatic Position

Phylum -Chordata Subphylum - Vertebrata Superclass -Tetrapoda Class -Aves Subclass -Neornithes Superorder - Neognathae Order -Columbiformes Type -Columba livia

Fig 9.27 Pigeon

The large bird Columba (Pigeon) comprises a group of medium to large stout-bodied pigeons, often referred to as the typical pigeons. The terms "dove" and "pigeon" are used indiscriminately for smaller and larger Columbidae, respectively. Columbaspecies – at least those of Columba sensustricto – are generally termed "pigeons", and in many cases wood-pigeons. The species commonly referred to just as "the pigeon" is the feral pigeon (C. liviadomestica). It is derived from the rock pigeon(C. livia), which also has given rise to the majority of domesticated pigeon breeds, such as the racing pigeon. Meanwhile, "wood pigeon" by itself usually means the common wood pigeon (C. palumbus).

This genus as understood today is native to the Old World, but some – notably the domestic and feral rock pigeon – have been introduced outside their natural range, for example in the Americas.

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Etymology

The term columba comes from the Latin columba, "a dove", the feminine form of columbus, "a male dove",itself the latinisation of the Greek (kolumbos), "diver", which derives from the verb (kolumbaō), "to dive, plunge headlong, swim". The feminine form of kolumbos, (kolumbis), "diver", was the name applied by Aristophanesand others to the common rock pigeons of Greece, because of the "swimming" motion made by their wings when flying.

Systematic

The American pigeons formerly in Columba are now split off as a separate genus Patagioenas again. That the American radiation constitutes a distinct lineage is borne out by molecular evidence; in fact, the Patagioenas "pigeons" are basal to the split between the Columba "pigeons" and the Streptopelia "doves". The typical pigeons together with Streptopelia and the minor Nesoenas and Stigmatopelia lineages constitute the dominant evolutionary radiation of Columbidae in temperateEurasia, though they also occur in tropical regions. The taxonomic status of some African pigeons presently placed here is in need of further study; they are smaller than the usual Columba (and hence often called "doves"), and differ in some other aspects. They might be separable as genus Aplopelia. That notwithstanding, the lineage of the typical pigeons probably diverged from its closest relatives in the Late Miocene, perhaps some 7-8 million years ago .

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CHARACTERS OF ARCHAEOPTERYX

Scientific Position:

Kingdom : Animalia

Phylum: Chordata

Clade: Dinosauria

Order: Saurischia

Suborder: Theropoda

Clade: Avialae

Family: Archaeopterygidae

Genus : Archaeopteryx

Fig 9.28 Archaeopteryx

Archaeopteryx, sometimes referred to by its German name Urvogel ("original bird" or "first bird"), is a genus of bird-like dinosaurs that is transitional between non-avian feathered dinosaurs and modern birds. The name derives from the ancient Greek meaning "ancient", and meaning "feather" or "wing". Between the late nineteenth century and the early twenty-first century, Archaeopteryx had been generally accepted by palaeontologistsand popular reference books as the oldest known bird (member of the group Avialae).Older potential avialans have since been identified, including Anchiornis, Xiaotingia, and Aurornis.

Archaeopteryx lived in the Late Jurassic around 150 million years ago, in what is now southern Germany during a time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now. Similar in size to a Eurasian magpie, with the largest individuals possibly attaining the size of a raven, the largest species ofArchaeopteryx could grow to about 0.5 m (1 ft 8 in) in length. Despite their small size, broad

CHORDATA 16SCCZO3 01 wings, and inferred ability to fly or glide, Archaeopteryx had more in common with other small Mesozoic dinosaurs than with modern birds. In particular, they shared the following features with the dromaeosaurids and troodontids: jaws with sharp teeth, three fingers with claws, a long bony tail, hyperextensible second sstoes ("killing claw"), feathers (which also suggest warm-bloodedness), and various features of the skeleton.

These features make Archaeopteryx a clear candidate for a transitional fossil between non-avian dinosaurs and birds.Thus, Archaeopteryx plays an important role, not only in the study of the origin of birds, but in the study of dinosaurs. It was named from a single feather in 1861.[8] That same year, the first complete specimen of Archaeopteryx was announced. Over the years, ten more fossils of Archaeopteryx have surfaced. Despite variation among these fossils, most experts regard all the remains that have been discovered as belonging to a single species, although this is still debated.

Most of these eleven fossils include impressions of feathers. Because these feathers are of an advanced form (flight feathers), these fossils are evidence that the evolution of feathers began before the Late Jurassic. The type specimen ofArchaeopteryx was discovered just two years after Charles Darwin published On the Origin of Species. Archaeopteryxseemed to confirm Darwin's theories and has since become a key piece of evidence for the origin of birds, the transitional fossils debate, and confirmation of evolution.

FLIGHT ADAPTATION & BIRD MIGRATION

Bird migration is the regular seasonal movement, often north and south along a flyway, between breeding andwintering grounds. Many species of bird migrate. Migration carries high costs in predation and mortality, including from hunting by humans, and is driven primarily by availability of food. It occurs mainly in the northern hemisphere, where birds are funnelled on to specific routes by natural barriers such as the Mediterranean Seaor the Caribbean Sea.

Historically, migration has been recorded as much as 3,000 years ago by Ancient Greek authors including Homer and Aristotle, and in the Book of Job, for species such as storks, turtle doves, and swallows. More recently, Johannes Leche began recording dates of arrivals of spring migrants in Finland in 1749, and scientific studies have used techniques including bird ringing and satellite tracking. Threats to migratory birds have grown with habitat destruction

CHORDATA 16SCCZO3 01 especially of stopover and wintering sites, as well as structures such as power lines and wind farms.

The Arctic tern holds the long-distance migration record for birds, travelling between Arctic breeding grounds and the Antarctic each year. Some species of tubenoses (Procellariiformes) such as albatrosses circle the earth, flying over the southern oceans, while others such as Manx shearwaters migrate 14,000 km (8,700 mi) between their northern breeding grounds and the southern ocean. Shorter migrations are common, including altitudinal migrations on mountains such as the Andes and Himalayas.

The timing of migration seems to be controlled primarily by changes in day length. Migrating birds navigate using celestial cues from the sun and stars, the earth's magnetic field, and probably also mental maps.

Swallow migration versus hibernation:- Aristotle however suggested that swallows and other birds hibernated. This belief persisted as late as 1878, when Elliott Coues listed the titles of no less than 182 papers dealing with the hibernation of swallows. Even the "highly observant"Gilbert White, in his posthumously published 1789 The Natural History of Selborne, quoted a man's story about swallows being found in a chalk cliff collapse "while he was a schoolboy at Brighthelmstone", though the man denied being an eyewitness.However, he also writes that "as to swallows being found in a torpid state during the winter in the Isle of Wight or any part of this country, I never heard any such account worth attending to", and that if early swallows "happen to find frost and snow they immediately withdraw for a time—a circumstance this much more in favor of hiding than migration", since he doubts they would "return for a week or two to warmer latitudes".

General patterns:- Migration is the regular seasonal movement, often north and south, undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat, or weather. Sometimes, journeys are not termed "true migration" because they are irregular (nomadism, invasions, irruptions) or in only one direction (dispersal, movement of young away from natal area). Migration is marked by its annual seasonality. Non-migratory birds are said to be resident or sedentary. Approximately 1800 of the world's 10,000 bird species are long- distance migrants.

CHORDATA 16SCCZO3 01 Many bird populations migrate long distances along a flyway. The most common pattern involves flying north in the spring to breed in the temperate or Arctic summer and returning in the autumn to wintering grounds in warmer regions to the south. Of course, in the southern hemisphere the directions are reversed, but there is less land area in the far south to support long- distance migration.

The primary motivation for migration appears to be food; for example, some hummingbirds choose not to migrate if fed through the winter. Also, the longer days of the northern summer provide extended time for breeding birds to feed their young. This helpsdiurnal birds to produce larger clutches than related non-migratory species that remain in the tropics. As the days shorten in autumn, the birds return to warmer regions where the available food supply varies little with the season.

These advantages offset the high stress, physical exertion costs, and other risks of the migration. Predation can be heightened during migration: Eleonora's falcon Falco eleonorae, which breeds on Mediterranean islands, has a very late breeding season, coordinated with the autumn passage of southbound passerine migrants, which it feeds to its young. A similar strategy is adopted by the greater noctule bat, which preys on nocturnal passerine migrants. The higher concentrations of migrating birds at stopover sites make them prone to parasites and pathogens, which require a heightened immune response.

Within a species not all populations may be migratory; this is known as "partial migration". Partial migration is very common in the southern continents; in Australia, 44% of non-passerine birds and 32% of passerine species are partially migratory.In some species, the population at higher latitudes tends to be migratory and will often winter at lower latitude. The migrating birds bypass the latitudes where other populations may be sedentary, where suitable wintering habitats may already be occupied. This is an example of leap-frog migration.Many fully migratory species show leap-frog migration (birds that nest at higher latitudes spend the winter at lower latitudes), and many show the alternative, chain migration, where populations 'slide' more evenly north and south without reversing order.

CHORDATA 16SCCZO3 01 Long-Distance Migration:-

The typical image of migration is of northern landbirds, such as swallows (Hirundinidae) and birds of prey, making long flights to the tropics. However, many Holarctic wildfowl and finch (Fringillidae) species winter in the North Temperate Zone, in regions with milder winters than their summer breeding grounds. For example, the pink-footed goose Anserbrachyrhynchus migrates from Iceland to Britain and neighbouring countries, while the dark-eyed junco Juncohyemalismigrates from subarctic and arctic climates to the contiguous United States and the American goldfinch from taiga to wintering grounds extending from theAmerican South northwestward to Western Oregon.Migratory routes and wintering grounds are traditional and learned by young during their first migration with their parents. Some ducks, such as the garganey Anasquerquedula, move completely or partially into the tropics. The European pied flycatcher Ficedulahypoleucaalso follows this migratory trend, breeding in Asia and Europe and wintering in Africa.

Often, the migration route of a long-distance migrator bird doesn't follow a straight line between breeding and wintering grounds. Rather, it could follow a hooked or arched line, with detours around geographical barriers. For most land-birds, such barriers could consist in seas, large water bodies or high mountain ranges, because of the lack of stopover or feeding sites, or the lack of thermal columns for broad-winged birds.

In waders

A similar situation occurs with waders (called shorebirds in North America). Many species, such as dunlin Calidrisalpineand western sandpiper Calidrismauri, undertake long movements from their Arctic breeding grounds to warmer locations in the same hemisphere, but others such as semipalmated sandpiper C. pusilla travel longer distances to the tropics in the Southern Hemisphere.

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Fig 9.29 Shorebirds in North America

For some species of waders, migration success depends on the availability of certain key food resources at stopover points along the migration route. This gives the migrants an opportunity to refuel for the next leg of the voyage. Some examples of important stopover locations are the Bay of Fundy and Delaware Bay.

Some bar-tailed godwits Limosalapponica have the longest known non-stop flight of any migrant, flying 11,000 km fromAlaska to their New Zealand non-breeding areas.Prior to migration, 55 percent of their bodyweight is stored as fat to fuel this uninterrupted journey.

Diurnal migration in raptors:- Some large broad-winged birds rely on thermal columns of rising hot air to enable them to soar. These include many birds of prey such as vultures, eagles, and buzzards, but also storks. These birds migrate in the daytime. Migratory species in these groups have great difficulty crossing large bodies of water, since thermals only form over land, and these birds cannot maintain active flight for long distances. Mediterranean and other seas present a major obstacle to soaring birds, which must cross at the narrowest points. Massive numbers of large raptors and storks pass through areas such as the Strait of Messina, Gibraltar, Falsterbo, and the Bosphorus at migration times. More common species, such as the European honey buzzard Pernisapivorus, can be counted in hundreds

CHORDATA 16SCCZO3 01 of thousands in autumn. Other barriers, such as mountain ranges, can also cause funnelling, particularly of large diurnal migrants. This is a notable factor in the Central Americanmigratory bottleneck. Batumi bottleneck in the Caucasus is one of the heaviest migratory funnels on earth. Avoiding flying over the Black Sea surface and across high mountains, hundreds of thousands of soaring birds funnel through an area around the city of Batumi, Georgia. Birds of prey such as honey buzzards which migrate using thermals lose only 10 to 20% of their weight during migration, which may explain why they forage less during migration than do smaller birds of prey with more active flight such as falcons, hawks and harriers.

Nocturnal migration in smaller insectivorous birds:- Many of the smaller insectivorous birds including the warblers, hummingbirds and flycatchers migrate large distances, usually at night. They land in the morning and may feed for a few days before resuming their migration. The birds are referred to as passage migrants in the regions where they occur for short durations between the origin and destination.

Nocturnal migrants minimize predation, avoid overheating, and can feed during the day.One cost of nocturnal migration is the loss of sleep. Migrants may be able to alter their quality of sleep to compensate for the loss.

Short-distance and altitudinal migration:-

Many long-distance migrants appear to be genetically programmed to respond to changing day length. Species that move short distances, however, may not need such a timing mechanism, instead moving in response to local weather conditions. Thus mountain and moorland breeders, such as wallcreeper Tichodromamuraria and white- throated dipper Cincluscinclus, may move only altitudinally to escape the cold higher ground. Other species such as merlin Falco columbarius and Eurasian skylark Alaudaarvensis move further, to the coast or towards the south. Species like the chaffinch are much less migratory in Britain than those of continental Europe, mostly not moving more than 5 km in their lives.

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Fig 9.30 Short distance migration in birds

Short-distance passerine migrants have two evolutionary origins. Those that have long-distance migrants in the same family, such as the common chiffchaff Phylloscopuscollybita, are species of southern hemisphere origins that have progressively shortened their return migration to stay in the northern hemisphere.

Species that have no long-distance migratory relatives, such as the waxwings Bombycilla, are effectively moving in response to winter weather and the loss of their usual winter food, rather than enhanced breeding opportunities.

In the tropics there is little variation in the length of day throughout the year, and it is always warm enough for a food supply, but altitudinal migration occurs in some tropical birds. There is evidence that this enables the migrants to obtain more of their preferred foods such as fruits.

Altitudinal migration is common on mountains worldwide, such as in the Himalayas and the Andes.

Irruptions and dispersal

Sometimes circumstances such as a good breeding season followed by a food source failure the following year lead to irruptions in which large numbers of a species move far beyond the normal range. Bohemian waxwings Bombycillagarrulous well show this unpredictable variation in annual numbers, with five major arrivals in Britain during the nineteenth century, but 18

CHORDATA 16SCCZO3 01 between the years 1937 and 2000. Red crossbills Loxiacurvirostra too are irruptive, with widespread invasions across England noted in 1251, 1593, 1757, and 1791.

Evolutionary and ecological factors:- Migration in birds is highly labile and is believed to have developed independently in many avian lineages. While it is agreed that the behavioral and physiological adaptations necessary for migration are under genetic control, some authors have argued that no genetic change is necessary for migratory behavior to develop in a sedentary species because the genetic framework for migratory behavior exists in nearly all avian lineages. This explains the rapid appearance of migratory behavior after the most recent glacial maximum.

Climate change:-

Large scale climatic changes, as have been experienced in the past, are expected to have an effect on the timing of migration. Studies have shown a variety of effects including timing changes in migration, breeding as well as population variations.

Ecological effects:-

The migration of birds also aids the movement of other species, including those of ectoparasites such as ticks and lice, which in turn may carry micro-organisms including those of concern to human health. Due to the global spread of avian influenza, bird migration has been studied as a possible mechanism of disease transmission, but it has been found not to present a special risk; import of pet and domestic birds is a greater threat.Some viruses that are maintained in birds without lethal effects, such as the West Nile Virus may however be spread by migrating birds. Birds may also have a role in the dispersal of propagules of plants and plankton.

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SUMMARY

Aves are the Latin name for the birds - feathered, winged bipedal, warm-blooded, egg-laying, vertebrate animals with evolutionary origins among the reptiles. The taxon has been historically treated as equal to fish, amphibian, reptiles and mammals, but in order to make classifications reflect evolutionary history, they are now more usually regarded as falling inside the Reptilian. Around 10,000 living species makes them the most species class of tetra pod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from the 5 cm Bee Hummingbird to the 2.75 m Ostrich. The fossil record indicates that birds evolved from there of dinosaurs during the Jurassic period, around 160 million years (Ma) ago. Birds are the only clade of dinosaurs to have survived the Cretaceous “Paleogene extinction event 65.5 Ma ago. Modern birds are characterized by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All living species of birds have wings. Wings are evolved forelimbs, and most bird species can fly; exceptions include the ostriches, emus and relatives, penguins, and some endemic island species. Birds also have unique digestive and respiratory systems that are well suited to their flying needs. Some birds, especially corvids and parrots, are among the most intelligent animal species; a number of bird species have been observed manufacturing and using tools, and many social species transmit knowledge across generations. Many species undertake long distance annual migrations, and many more perform shorter irregular movements.Many species are social and communicate using visual signals and through calls and songs, and participate in social behaviours, including cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, and rarely for life. Other species have polygynous (\"many females\") or, rarely, polyandrous (\"many males\") breeding systems. Eggs are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching. Many species are of economic importance, mostly as sources of food acquired through hunting or farming. Some species, particularly songbirds and parrots, are popular as pets. Other uses include the harvesting of guano (droppings) for use as a fertiliser. Birds figure prominently in all aspects of human culture from religion to poetry to popular

CHORDATA 16SCCZO3 01 music. About 120â “130 species have become extinct as a result of human activity since the 17th century and hundreds more before then. Currently about 1,200 species of birds are threatened with extinction by human activities, though efforts are underway to protect them.

GLOSSARY

Asymmetric - Not the same on each side of the body Atmospheric pollution -Pollution of the air Aves - the Latin word for birds; a special class of vertebrates Binocular vision - seeing only one object at a time; both eyes focus on the same object Bird of prey - a carnivorous bird (hawk, falcon, eagle, etc.) that kills and eats small Mammals and other birds Botulism - Poisoning from spoiled food Carnivore - Meat eater Carrion - decaying flesh of a dead body Cere - fleshy area above the beak, where the nostrils of most birds are located Cold-Blooded- animals that can only control their body temperatures by moving into warmer or cooler areas Concave- Wings that is flat or slightly curved on the bottom Cones - Cells of the eye sensitive to color Conserving Energy -To keep from using energy by resting or gliding when possible Contour Feathers- stiff feathers designed to cover the wings and body of a bird Convex- Wings that are curved on top Crop- a large sac between the esophagus and stomach that stores food until the Bird is ready to begin digestion Diurnal - Daytime hunters Domestic - Any animal used by man - not wild Down Feathers - fluffy feathers designed to help insulate and keep a bird warm Drag - anything that hinders or hampers the speed; something that pulls you Down

CHORDATA 16SCCZO3 01 Electrocution- Injury or death from electricity Environmental Contamination- Pollution of the environment Esophagus- Portion of the body that connects the mouth with the stomach Falconiformes- Related to falcons; hawks, osprey, eagles, etc Fledge - the rearing of a young bird until it has grown its feathers and is able to fly And leave the nest Flight Feathers- special contour feathers that help a bird get off the ground, move in the air, And land safely Foragers- Scavenge for food - eats discarded food Fovea - a rodless area of the retina enabling a bird of prey acute vision Gizzard - a special muscle of the stomach that helps the digestive process by grinding and crushing hard-to-digest food; acts like teeth Incubating - Keep eggs warm until hatching.

TERMINAL QUESTION ANSWERS

Q1 Give the classification on the order level of Pigeon. Q2 Give the introduction of Pigeon. Q3 Explain the different type of migration. Q4 Give an account of flight mechanism in birds. Q5 Give an account of structure an affinities of Archaeopteryx?

Multiple Choice Questions

1 The study of birds is termed as: (a) Ornithology (b) Oology (c) Herpetology (d) Ichthyology

CHORDATA 16SCCZO3 01 2 Witch of the following is not true for birds (a) Feathered (b) Flying (c) Quadraped (d) Possess wing

3 The only cutaneous gland in pigeon (a) Sweat gland (b) Sebaceous gland (c) Mammary gland (d) Preen gland uropygial gland

4 In bird gizzard is used (a) Chewing food (b) Grinding food (c) Mixing food (d) Digesting food

5 In birds voluntary movements are controlled by: (a) Cerebellum (b) Optic lobes (c) Cruracerbri (d) Medulla oblongata

6 In birds, sound is produced by: (a) Air sac (b) Trachea (c) Larynx (d) Syrinx

CHORDATA 16SCCZO3 01 7 The fossil record of Archaeopteryx have been discovered from: (a) Britain (b) Germany (c) France (d) USA

8 Birds are glorified (a) Vertebrates (b) Fishes (c) Amphibians (d) Reptiles

9 The most common mode of flight (a) Flapping (b) Gliding (c) Soaring (d) Hovering

10 Beak in sparrows is (a) Cutting type (b) Seed eating type (c) Fruit eating type (d) Tearing and piercing type

Answers

1(a)2(c ) 3(d)4(b)5(d)6 (d)7 (b)8(d)9(a)10(b)

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REFERENCES

1. Jordan E.L. and P.S. Verma 1995.Chordate Zoology and Elements of Animal Physiology.S.Chand and Co.New Delhi 2. Kotpal, R.L 2012.Vertebrata, Rastogi publication Merruth. 3. Nigam,H.C.1983.Zoology of chordates,Vishal publication,Jalandhar 4. Some figure and tax material are adopted from Wikipedia. 5. Some figure and tax material are adopted from Biozoom

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UNIT: 10 MAMMALIA

CONTENT

Objective

Introduction

General Characteristics of Mammalia

Classification of Mammalia

Affinities of Prototheria

Affinities of Metatheria

Affinities of Eutheria

Study of rabbit (Oryctolagus) and dentition in mammals.

Summary

Glossary

Self Assessment Question

Terminal Question Answers

References

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OBJECTIVE

a) To understand the systematics and functional morphology of various groups of Mammalia. b) To study the general characters and classification of class Mammalia. c) To study the affinities of Prototheria, Metatheria and Eutheria. d) To Study a type specimen of mammalia- Rabbit. e) To study the dentition in mammals. f) To study and economic importance of mammals.

INTRODUCTION

Mammals include the largest animals on the planet, the great whales, as well as some of the most intelligent, such as elephants, primates and cetaceans. The basic body type terrestrial quadruped, but some mammals are adapted for life in sea, in the air, on trees, underground or on two legs. The largest group of mammals, the placental, have a placenta, which enables range in size from the 30–40 mm (1.2–1.6 in) (108 ft) blue whale,With the exception of the five species of monotreme (egg-laying mammals), all modern mammals give birth to live young. Most mammals, including the six most species-rich orders, belong to the placental group. The three largest orders in number of species are Rodentia i.e mice, rats, porcupines, beavers, capybaras and other gnawing mammals; Chiroptera i.e bats; and Soricomorpha: shrews, moles and solenodons. The next three biggeorders, depending on the biological classification scheme used, are the Primates including the great apes and monkeys; the Cetartiodactyla including whales and even-toed ungulates; and the Carnivora which includes cats, dogs, weasels, bears and seals The word "mammal" is modern, from the scientific name Mammalia, coined by Carl Linnaeus in 1758, derived from the Latin mamma ("teat, pap"). All female mammals nurse their young with milk, which is secreted from special glands, i.e mammary glands. According to Mammalian Species of the World, 5,416 species were known in 2006. These were grouped in 1,229 genera, 153 families and 29 orders. In 2008 the International Union for Conservation of Nature (IUCN) completed a five-year, 1,700- scientist Global Mammal Assessment for its IUCN Red List, which counted 5,488 species. In

CHORDATA 16SCCZO3 01 some classifications, extant mammals are divided into two subclasses: the Prototheria, that is, the order Monotremata; and the Theria, or the infraclasses Metatheria and Eutheria. The marsupials constitute the crown group of the Metatheria, and include all living metatherians as well as many extinct ones; the placentals are the crown group of the Eutheria. While mammal classification at the family level has been relatively stable, several contending classifications regarding the higher levels subclass, infraclass and order.

Fig 10.1 Animals of the class mammalian(Mammals)

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GENERAL CHARACTERISTICS OF MAMMALIA

Characteristics of Class Mammalia are given below:- a) They are Warm blooded. b) Possess hair which is made of keratin. The evolution of mammalian keratin is believed to be independent of reptilian keratin. Hair provides insulation. c) Endothermic. The majority of the heat energy is used to maintain their high body temperature. d) Four chambered heart. e) Mammary glands are used to produce milk to nourish their young. Female glands are the only functional glands. f) Thediaphragm is a muscle that separates the thoracic cavity from the abdominal cavity. g) Seven cervical vertebrae (neck bones) are present in most mammals. h) Most are viviparous though some are oviparous. An extended gestation period uterine development is common in most placental mammals. i) Teeth are imbedded in the jaw bone and come in a variety of forms. j) Well-developed brain. k) Mammals developed from the therapsid ancestors during the Triassic period. l) Mammals are heterodontic, meaning that their teeth are different shapes, except those with no teeth at all. m) Reptiles and fish have teeth that are all basically the same, though they can vary in size throughout the mouth. See image above. n) The Buccal Cavity (the mouth) has a false palate as a roof, meaning that the nostrils do not lead directly into his mouth. o) The body is maintained at a constant temperature they generate heat within their bodies metabolically and also have special cooling mechanisms. p) Highly developed neopallium. q) Tectum reduced to corpora quadrigemina: functions mainly as a relay center for auditory information and to control visual reflexes. r) Corpus callosum in eutherians provides additional communication s) Smell acute except whales and higher apes.

CHORDATA 16SCCZO3 01 t) Eye typical of amniotes. u) Tapetum lucidum well developed in nocturnal mammals. v) Touch- most have vibrissae that are controlled by facial muscles. w) Lateral movement of jaw during mastication. x) Viviparous except monotremes which are egg laying. y) Parental care well developed.

CLASSIFICATION OF MAMMALIA

Mammalia is a class of Phylum Chordate. Mammalian classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is universally accepted; McKenna & Bell (1997) and Wilson & Reader (2005) provide useful recent compendiums.Many earlier ideas have been completely abandoned by Linnaeus and modern taxonomists, among these are the idea that bats are related to birds or that humans represent a group outside of other living things. Competing ideas about the relationships of mammal orders do persist and are currently in development. Most significantly in recent years, cladistic thinking has led to an effort to ensure that all taxonomic designations represent monophyleticgroups. The field has also seen a recent surge in interest and modification due to the results of molecular phylogenetics.

George Gaylord Simpson's classic "Principles of Classification and a Classification of Mammals" (Simpson, 1945) taxonomy text laid out a systematics of mammal origins and relationships that was universally taught until the end of the 20th century

Since Simpson's 1945 classification, the paleontological record has been recalibrated, and the intervening years have seen much debate and progress concerning the theoretical underpinnings of systematization itself, partly through the new concept of cladistics. Though field work gradually made Simpson's classification outdated, it remained the closest thing to an official classification of mammals. See list of placental mammals and list of monotremes and marsupials for more detailed information on mammal genera and species.

CHORDATA 16SCCZO3 01 Subclass 1: Prototheria

(Gr., protos, first + therios, beast) Primitive, reptile-like, oviparous or egg laying animals.

1) Order 1 Monotremata • Family Tachyglossidae (Echidnas) &Family Ornithorhynchidae (Platypuses) Subclass: 2: Theria Infraclass Metatheria (marsupials and their nearest ancestors) 2) Order Didelphimorphia a) Family Didelphidae (opossums, etc.) 3) Order Paucituberculata a) Family Caenolestidae (shrew opossums) 4) Order Microbiotheria a) Family Microbiotheriidae (monito del montes) 5) Order Dasyuromorphia (most carnivorous marsupials)

a) Family Thylacinidae (Tasmanian tigers), Family Myrmecobiidae (numbats) b) Family Dasyuridae (Tasmanian devils, quolls, dunnarts, planigale, etc.)

6) Order Peramelemorphia (bandicoots, bilbies, etc.) a) Family Peramelidae&Family Peroryctidae 7) Order Notoryctemorphia (marsupial moles) a) Family Notoryctidae 8) Order Diprotodontia a) Family Phascolarctidae (koalas), Family Vombatidae (wombats)

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Fig.10.2 Example of Prototheria

b) Family Phalangeridae (brushtail possums and cuscuses)

Infraclass Eutheria

9) Order Xenarthra a) Family Bradypodidae, Family: Megalonychidae, Family: Dasypodidae b) Family: Myrmecophagidae

10) Order Insectivora a) Family Solenodontidae, Family Nesophontidae b) Family Tenrecidae, Family Chrysochloridae c) Family Erinaceidae, Family Soricidae d) Family Talpidae Fig 10.3 Example of Eutheria

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11) Order Scandentia a) Family: Tupaiidae 12) Order Dermoptera a) Family: Cynocephalidae 13) Order Chiroptera a) Family :Pteropodidae, Family: Emballonuridae, Family: Craseonycteridae, Family: Rhinopomatidae, Family: Nycteridae, Family: Megadermatidae, Family: Rhinolophidae 14) Order Primates a) Family: Daubentoniidae, Family: Lemuridae , Family: Lepilemuridae b) Family: Galagidae, Family: Lorisidae, Family: Cheirogaleidae,

15) Order Carnivora a) Family: Felidae, Family: Viverridae, Family: Herpestidae b) Family: Hyaenidae, Family: Canidae, Family: Ursidae 16) Cetacea a) Family :Balaenopteridae, Family: Eschrichtiidae, Family: Balaenidae b) Family: Neobalaenidae, Family: Physeteridae, Family: Ziphiidae 17) Order Sirenia a) Family: Dugongidae, b) Family :Trichechidae

Fig 10.4Manatee vs Dugong

CHORDATA 16SCCZO3 01 18) Order Proboscidea a) Family Elephantidae

19) Order Perissodactyla a) Family Equidae, Family Tapiridae, Family Rhinocerotidae

20) Order Hyracoidea a) Family Procaviidae

21) Order Tubulidentata Fig 10.5 a) Family Orycteropodidae

22) Order Artiodactyla a) Family Suidae, Family Tayassuidae, Family Hippopotamidae b) Family Camelidae, Family Tragulidae, Family Giraffidae

23) Order Pholidota a) Family Manidae

24) Order Rodentia a) Family Aplodontiidae, Family Sciuridae, Family Castoridae b) Family Geomyidae, Family Heteromyidae, Family Dipodidae c) Family Muridae, Family Anomaluridae, Family Pedetidae d) Family Ctenodactylidae, Family Myoxidae, Family Bathyergidae

25) Order Lagomorpha a) Family Ochotonidae

26) Order Macroscelidea

CHORDATA 16SCCZO3 01 a) Family Macroscelididae

Subclass Prototheria 27) Order Platypoda: platypuses a) Family Ornithorhynchidae: platypuses 28) Order Tachyglossa: echidnas (spiny anteaters) a) Family Tachyglossidae: echidnas Subclass Theriiformes a) Infraclass -Allotheria 29) Order Multituberculata: multituberculates a) Family Plagiaulacidae 30) Super legion Kuehneotheria a) Family Kuehneotheriidae b) Family Woutersiidae 31) Super legion Trechnotheria a) Legion Symmetrodonta 30. Order Amphidontoidea a) FamilyAmphidontidae 31. Order Spalacotherioidea a) FamilyTinodontidae 32) Legion Cladotheria a) Sublegion †Dryolestoidea 32. Order Dryolestida a) Family Austrotriconodontidae b) Family Dryolestidae 33. Order Amphitheriida a) Family Amphitheriidae 33) Sublegion Zatheria a) Family Arguitheriidae 34) InfralegionPeramura a) Family Peramuridae

CHORDATA 16SCCZO3 01 35) Infralegion Tribosphenida a) Family Necrolestidae SupercohortAegialodontia a) Family Aegialodontidae Supercohort Theria: therian mammals b) Family Pappotheriidae c) Family Plicatodontidae Order Deltatheroida a) Family Deltatheridiidae b) Family Deltatheroididae Order Asiadelphia a) Family Asiatheriidae Superorder Microbiotheria a) Family Microbiotheriidae: monito del monte Superorder Eometatheria 43) Order Yalkaparidontia a) Family Yalkaparidontidae 44) Order Notoryctemorphia: marsupial moles a) Family Notoryctidae: marsupial moles 45) Order Peramelia: bandicoots a) Family Peramelidae b) Family Peroryctidae 46) Order Diprotodontia a) Family †Palorchestidae 47) Order Didelphimorphia: opossums a) Family Didelphidae: opossums 48) Order Paucituberculata a) Family Sternbergiidae 49) Order Sparassodonta a) Family Mayulestidae

CHORDATA 16SCCZO3 01 50) Order Cingulata: armadillos and relatives a) Family Dasypodidae: armadillos 51) Order Pilosa: anteaters, sloths, and relatives a) Family Entelopidae b) Family Myrmecophagidae: giant anteaters and relatives Magnorder Epitheria: epitheres 52) Superorder Leptictida a) Family Gypsonictopidae b) Family Kulbeckiidae 53) Superorder Preptotheria 54) Grandorder Anagalida a) Family Zambdalestidae 55) Mirorder Macroscelidea: elephant shrews a) Family Macroscelididae: elephant shrews Mirorder Duplicidentata 56) Order Mimotonida a) Family Mimotonidae 57) Order Lagomorpha a) Family Ochotonidae: pikas 58) Mirorder Simplicidentata 58) Order Mixodontia a) Family Eurymylidae 59) Order Rodentia: rodents a) Family Alagomyidae. Family Thryonomyidae: cane rats Grandorder Ferae 60) Order Cimolesta - pangolins and relatives a) Family Palaeoryctidae, Family †Cimolestidae, Family †Apatemyidae 61) Order Creodonta: creodonts a) Family Hyaenodontidae, Family †Oxyaenidae 62) Order Carnivora

CHORDATA 16SCCZO3 01 a) Family Viverravidae, Family †Nimravidae, Family Procyonidae: ringtails, olingos, kinkajou, raccoons, coatis, red panda 63) Order Chrysochloridea a) Family Chrysochloridae: golden moles 64) Order Erinaceomorpha a) Family Sespedectidae, Family Amphilemuridae 65) Order Soricomorpha a) Family †Otlestidae, Family Geolabididae 66) Order Chiroptera: bats a) Family Pteropodidae: flying foxes, Family Archaeonycteridae 67) Order Primates: primates a) Family †Purgatoriidae, Family Microsyopidae 68) Order Scandentia a) Family Tupaiidae: tree shrew Grandorder Ungulata: ungulates 69) Order Tubulidentata a) Family Orycteropodidae: aardvark 70) Order Dinocerata a) Family Uintatheriidae Mirorder Eparctocyona 71) Order Procreodi a) Family Oxyclaenidae, Family †Arctocyonidae 72) Order Condylarthra 73) Order Arctostylopida a) Family Arctostylopidae 74) Order Cete: whales and relatives a) Family Triisodontidae, Family Mesonychidae: mesonychids 75) Order Artiodactyla: even-toed ungulates a) Family Raoellidae, Family Hippopotamidae: hippos 76) Order Litopterna a) Family Protolipternidae, Family Macraucheniidae

CHORDATA 16SCCZO3 01 77) Order Notoungulata: notoungulates a) Family Henricosborniidae, Family Notostylopidae 78) Order Astrapotheria a) Family Eoastrapostylopidae, Family Trigonostylopidae 79) Order Xenungulata a) Family Carodniidae 80) Order Pyrotheria a) Family Pyrotheriidae Mirorder Altungulata 81) Order Perissodactyla: odd-toed ungulates a) Family Equidae: horses, Family Palaeotheriidae 82) Order Uranotheria: elephants, manatees, hyraxes, and relatives a) Family Pliohyracidae, Family Procaviidae: hyraxes

AFFINITIES OF PROTOTHERIA

a) The prototheria are described as primitive unfinished mammals by Romer.

b) The mammary glands of prototheria are modified sweat glands unlike the Eutheria. Teatless mammary glands are characteristic of prototheria.

c) Males possess functional mammary glands. The feeding of young with milk by father and mother (parents) 'is known as gynaecomastism.

d) Auditory pinna or external ear is absent.

e) The skull is without tympanic bulla and lacrimals. Vertebrae are without epiphyses.

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Fig 10.6 Monotremes vs Prototheria

f) Cervical vertebrae bear ribs. Ribs are single headed having capitulum only. A large coracoid with precoracoid and a T shaped interclavicle is present in pectoral girdle.

g) The pelvic girdle has a pair of epipubic bones which are absent in eutherians.

h) The body temperature is low and ranges from 25° C to 28°C. Hence, they are described as heterothermous mammals. i) A cloaca is present into which ureters and urinogenital ducts open. Oviducts remain separate throughout the length and open into the cloaca.

j) Testes are abdominal. Penis helps to passout the sperms only.

k) There is no corpus callosum in the brain.

l) Teeth are present only in young ones; adults lack teeth, but a horny beak is present.

m) Females are oviparous laying large eggs with much amount of yolk (megalecithal).

n) Optic lobes are 4 in numbered.

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o) Prototherians possess a number of reptilian characters in addition to the mammalian characters. So they form the bridge to fill the gap between reptiles and mammals, i.e they act as connecting link between Reptiles and Mammals.

Reptilian features of Monotremes

a) A large coracoid with precoracoid and T-shaped interclavicle in pectoral girdle. b) Pelvic girdle is with epipubic bone. c) Vertebrae are without epiphyses. Ribs are single headed. d) Cloaca is present and testes are abdominal. e) Lying of large eggs with abundant yolk. f) Meroblastic cleavage is seen in the development.

Mammalian features of Monotremes

a) Hair is present all over the body. b) Diaphragm is present. c) Only left aortic arch is present. d) Heart is 4 chambered. e) Non-nucleated red blood corpuscles are seen in blood. f) Mid brain shows four optic lobes. g) Skin possesses mammary, sweat and sebaceous glands. h) Three ear ossicles are present in the middle ear. i) A single bone (dentary) is present in each half of the lower jaw. j) A slightly coiled cochlea is present.

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Prototheria includes only one living order Monotremata. It includes 3 living genera. These are found in Australia, Tasmania and New Guinea.

a) Ornithorynchus or duck billed platypus: It is distributed in Australia and Tasmania.

Fig.10.6 Macropus rufus

b) Echidna or Tachyglossus or spiny ant eater: It is found in Tasmania and New Guinea. c) Zaglossus or Proechidna: It is found in New Guinea and resemblesTachyglossus.

AFFINITIES OF METATHERIANS

Metatheria or Marsupials are more advanced than the prototherians. They are all pouched mammals characterised by the presence of an integumentary brood pouch or marsupium in which the immature young ones are fed with the milk of the mother.

The marsupials occupy an intermediate position between the primitive mammals (monotremes) and the higher mammals (eutherians).

CHORDATA 16SCCZO3 01 a) Marsupium or brood pouch is present in females. The mammary glands are present in the marsupium. b) The marsupium is supported by epipubic (marsupial) bones. c) The teeth are more in number. There are more than 3 incisors and more than 4 molars in each half of the jaw. Teeth are formed only once in life time. Hence, the dentition is called monophyodont dentition. d) Corpus callosum is usually absent in the brain and Placenta is absent. e) Although the anal and urinogenital apertures are separate and distinct, they are surrounded and controlled by a common sphincter muscle. f) Testes are situated in scrotal sacs. The penis is present behind the scrotum and it is bifid. g) The females have 2 oviducts, 2 uteri and 2 vaginae (didelphic condition) which separately open into urinogenital sinus. h) The young ones are born naked and blind, but they posses clawed fore limbs by which they move into the brood pouch. i) Fertilization and a major part of development are internal, but the young ones are born in immature state (mammary foetus). j) Yolk sac placenta is present in marsupialia. True allantoic placenta is absent (except parameles). Yolk sac is large with villi. k) Hind limbs are long in some animals like kangaroo. l) The body temperature ranges from 36° C to 40° C.

Marsupials exhibit discontinuous distribution. Some marsupial’s like kangaroos live in Australia and oppossums live in South America. Australia is described as the land of marsupials. Eg: Thylacinus (Tasmanean wolf) is a carnivorous marsupial. Notoryctus (Marsupial mole) is a burrowing form. Phascolarctus (koala bear) is an arboreal form. Myrmecobius (banded ant eater). Parameles is a marsupial bandicoot. Macropus (Kangaroo) is the largest marsupial. Didelphls marsupialis (American opposum).

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AFFINITIES OF EUTHERIA

EUTHERIA OR PLACENTALIA- SALIENT FETURES

Fig 10.6 (A) Armadillo (B) Tiger (C) Pangolin (D) Blue Whale

a) These are highly evolved mammals with advanced organization. b) Marsupium and marsupial bones are entirely absent. c) Nourishment, respiration and excretion of young takes place through a complex allantoic placenta. The young ones are born in relatively advanced state (miniature adults). Complete development takes place in the uterus only. Gestation period is generally long. d) Testes are usually present in scrotal sacs. Penis is situated infront of the testes. e) Vagina is single. Urinogenital passage and anus are separate f) Cerebral hemispheres in brain have more convolutions. Corpus callosum is well developed. Eutherians are viviparous. Its distribution is world-wide.

CHORDATA 16SCCZO3 01 Eg: Rats, bats, rabbits, monkeys, cats, dogs, whales, horses, deers, pigs, elephants, man etc.

STUDY OF RABBIT (ORYCTOLAGUS) AND DENTITION IN MAMMALS

Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world. There are eight different genera in the family classified as rabbits, including the European rabbit (Oryctolaguscuniculus), cottontail rabbits (genus Sylvilagus; 13 species), and the Amami rabbit (Pentalagusfurnessi, an endangered species on AmamiŌshima, Japan). There are many other species of rabbit, and these, along with pikas and hares, make up the order Lagomorpha. The male is called a buck and the female is a doe; a young rabbit is a kitten or kit.

Habitat of Rabbit:

Habitats of Rabits include meadows, woods, forests, grasslands, deserts and wetlands.Rabbits live in groups, and the best known species, the European rabbit, lives in underground burrows, or rabbit holes. A group of burrows is called a warren.

More than half the world's rabbit population resides in North America. They are also native to southwestern Europe, Southeast Asia,Sumatra, some islands of Japan, and in parts of Africa and South America. They are not naturally found in most of Eurasia, where a number of species of hares are present. Rabbits first entered South America relatively recently, as part of the Great American Interchange. Much of the continent has just one species of rabbit, the tapeti, while most of South America's southern cone is without rabbits.The European rabbit has been introduced to many places around the world.

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Systematic Position

Phylum: Chordata

Subphylum: Vertebreta

Superclass: Tetrapoda

Class: Mammalia

Subclass: Theria

Order: Lagomorpha

Family: Leporidae

Type: Orchtolagcuniculus (Rabbit)

Fig 10.7 Rabbit

The rabbit is brown in colour. It is about 40 cm in long and it weighs 2 to 4 pounds. The entire body is covered with a soft uniform hairy coat or fur. The body is divisible into four parts namely- head, neck, trunk and tail.

The head is elongated and produced into a pointed snout. The mouth is a transverse slit on the ventral side of the snout. It is bounded by two lips- upper lip and lower lip. The upper lip has a cleft interest middle through which the incisor teeth are clearly visible. Such a lip is called harelip. The sides of the upper lip produce stiff long thick hairs called vibrissae or whiskers. They are tactile sensory organs.

The external nares or nostrils are a pair of large oval slits just above the mouth. Two lines are present on the sides of the sides of the head. They are protected an upper and a lower eyelids. A third eyelid called nictitating membrane is also present on the inner corner of the eye. The top of the head bears a pair of sound collecting lobes called ear pinnae. The pinna acts as a radar antenna. The basal part of each pinna has tubular ear opening called external auditory meatus.

CHORDATA 16SCCZO3 01 This opening is closed below by a tympanic membrane or ear drum. The neck is short and permits the free movement of the head.

The Trunk is divisible into an anterior thorax and posterior abdomen. The ventral side of the abdomen is provided with 4 or 5 pair of teats or nipples. The teats are rudimentary in males. The anus is the present at the posterior end of the abdomen. On either side of the anus is a hairless depression called perineal pouches. The perineal scent glands lying inside open into these pouches. The secretions of these glands give the characteristics odour of the rabbit. In the male rabbit, the urinogenital aperture lies at the tip of penis (a muscular copulatory organ). The testes are lodged in two skin-bags called scrotal sacs which are present on either side of the penis. Instead in the female a vulva, the slit like aperture lies below the anus.

The trunk bears two pairs of limbs namely fore limbs and hind limbs. Each fore limb is divided into 3 parts namely a proximal upper branch (brachium), middle forearm (antebrachium) and a distal hand (manus). The hand is further divided into 3 parts namely wrist (carpus) and the palm (metacarpus) and the digits (fingers) with claws. The hind limb is also divided into thigh, the shank (crus) and the foot (pes). The foot is further sub-divided into an ankle (tarsus), a metatarsus and five toes with claws. The tail is hort and bushy and is located at the posterior end of the trunk.growing mass of cells. Cells of the outer layer of dermal papilla.

Fig.10.8 Dental structure in Rabbit

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DEVLOPMENT OF TOOTH:

Teeth develop over the jaw bone where certain malpighian cells start actively multiplying forming a mass of cells called dental lamina or enamel organ. A dental papilla made of group of dermal cells appears below the dental lamina that supplies nourishment to the arrange themselves in a row and get differentiated into odontoblast cells. Epidermal cells of the dental lamina that cover the growing dentine are called ameloblasts. The tooth gradually grows outwards and eventually gets exposed by penetrating through the skin covering the jaw bone. The dental papilla inside the pulp cavity remains active along with its blood supply and nerve intact. This development of tooth is identical to the development of dermal scales in fishes. Hence shark teeth are also called modified placoid scales.

DENTITION IN MAMMALS:

Mammals as a rule possess heterodont ,diphyodont and thecodont dentition. However, some mammals lack teeth as given below in detail.

a) Among monotremes, the spiny anteater or echidna (Tachyglossus and Zaglossus) lacks teeth b) Among the aquatic Cetacea baleen whales have no teeth, such as the blue whale, Balaenopteramusculus and, the whalebone whale. Among humans, and astonishingly, males in “Bhudas” tribe of Hyderabad Sindh in Pakistan c) They are genetically so predisposed that they never grow teeth all their lives.

The Dental Formula: Mammals have heterodont dentition having four types of teeth meant for different function in handling food in the oral cavity. Incisors in front are flat teeth designed for cutting food into pieces and the canines next to them are generally long and pointed spike-like used for tearing flesh by carnivore animals. Premolars and molars are located on the posterior side of the jaw, have flat surface with tubercles called cusps and are used for grinding food of plant origin. They are therefore well developed in herbivore animals. Number and arrangement of teeth in

CHORDATA 16SCCZO3 01 mammals is specific in different groups of animals so much so that mammalian orders can be identified by their teeth and dental formula, which is written for one half of the upper and lower jaw as follows.

TYPES OF TEETH

Polyphyodont dentition involves replacement of teeth from time to time several times in lifetime so that jaws are never left without teeth. Lower vertebrates having loose attachment of teeth lose teeth while feeding and capturing prey and hence teeth must grow again to replace the lost ones.

Diphyodont dentition is a characteristic of mammals in which milk teeth appear in the young ones but as they grow and jaw becomes larger, milk teeth are replaced by larger permanent ones to fit in the larger jaw bone.

Monophyodont teeth appear only once in lifetime and if they fall they are never again replaced by the new ones. Toothless animals have this kind of teeth and marsupials retain their milk teeth.

Based on the type of attachment of teeth on the jaw bone the following three types are found in vertebrates:

Acrodont teeth are attached on the top surface of the jaw bone as in fish and amphibians. This type of attachment is not very strong and teeth are lost easily and are replaced by new ones.

Pleurodontteeth are attached on the inner side and uppper side of the jawbone that brings larger surface area of tooth in contact with jawbone and hence attachment is stronger, as in lizards and urodeles. But this attachment is also not as strong as thecodont.

Thecodont dentition is found in mammals in which root of the tooth is firmly fixed in a socket of the jawbone, making the attachment strongest in vertebrates. This is a peg and socket attachment with the help of cementum that surrounds the root portion of the tooth.

CHORDATA 16SCCZO3 01 Based on the kinds of teeth found there are two types of dentition:

Homodont dentition is found in the majority of vertebrates such as fish, amphibia and reptiles in which all teeth are functionally and anatomically of the same type, although their size may be variable depending on the location. Sometimes functionally some teeth may be specialized as fangs of snakes.

Heterodont dentition occurs in mammals in which there are 4 functionally different types of teeth, namely, flat incisors for cutting, long and pointed canines for tearing flesh and large and broad premolars and molars with flat grinding surface. Molars have no counterparts in the milk teeth.

There are also some other type of teeth as follows:

Secodont teeth have sharp cutting edges that function like scissors to cut flesh as in some primates and in carnivores.

Bunodont teeth are small with smaller cusps or tubercles on the surface for handling soft diet as in man, monkeys, rodents etc.

Brachydont teeth are smaller and low crowned suitable for feeding on soft diet.

Hypsodont teeth possess larger crown that can resist wear and tear of feeding on tough and fibrous diet as in ungulates.

Selenodont teeth are found in horses and other ungulates in which silica deposit around cusps and in the depressions of the grinding surface.This makes the grinding surface of teeth harder to prevent wearing.

Lophodontteeth are found in elephants which feed on the roughest diet that any mammal can feed on.The ridges on the grinding surface are in the shape of rounded lophs and the depressions are filled with silica.

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SUMMARY

Mammals are a well-known class of vertebrates, including many familiar domesticated species and pets, as well as our own species Homo sapiens. All mammals are warm-blooded, and all female mammals possess mammary glands (mammae), which are used to suckle the young with milk. Mammals are further distinguished by the possession of hair or fur, although this is limited to early developmental stages in the Cetacea (whales and dolphins). The vast majority of mammals give birth to live young, the exception being the egg-laying Monotremata (a small group of mammals including the duck-billed platypus and the echidnas or spiny anteaters). Monotremes are found exclusively in Australia and New Guinea. Mammals are found in a wide variety of habitats, including terrestrial, freshwater, and marine systems. They occur from the deserts to the dense forests, from the deep seas to the highest mountains, and from the tropics to the polar ice caps. Only one group of mammals, the Chiroptera (bats) is adapted to flight; other taxa such as flying squirrels or flying possums can glide effectively but are not capable of true flight.

GLOSAARY

1) Altricial - Mammals that are born in relatively undeveloped condition (eyes closed and with minimal fur) and require prolonged parental care—as opposed to precocial. 2) Alveolar - Of or pertaining to an alveolus (plural, alveoli), a small cavity or pit, as a socket for a tooth. Alveolar length of a tooth-row therefore denotes the length of the row of the teeth, taken from the posteriormost place where the back tooth emerges from the bone to the anteriormost point where the front tooth in the row emerges from the bone—the overall length of the bony sockets for the row of teeth. 3) Angular process - The projection at the posterior, ventral end of the mammalian dentary. See "dentary".

CHORDATA 16SCCZO3 01 4) Annulation - A circular or ringlike formation, as of the dermal scales on the tail of a mammal where one ring of scales that extends entirely around the tail is succeeded, posteriorly, by other rings. 5) Arboreal - Inhabiting or frequenting trees—contrasted with fossorial, aquatic, and cursorial. 6) Auditory bulla (plural, auditory bullae) - A hollow, bony prominence of rounded form (in most mammals formed by the tympanic bone) partly enclosing structures of the middle and inner ear.

Ventral view of posterior skull of Nuttall's Cottontail Sylvilagus nuttallii, showing an auditory bulla (left); the wall of the right bulla has been broken, revealing the inside of the bulla. 7) Basal length - Distance on skull from the anteriormost inferior border of the foramen magnum to a line connecting the anteriormost parts of the premaxillary bones. 8) Basilar length - Distance on skull from the anteriormost inferior border of the foramen magnum to a line connecting the posteriormost margins of the alveoli of the first upper incisors. 9) Bead - A salient, rounded cordlike projecting ridge of bone, as in certain rodents where the superior border of the orbit is beaded. 10) Braincase - The part of the skull enclosing the brain. 11) Bunodont dentition - Referring to the cusp type of molars and/or premolars: cusps are low and rounded. The figure shows upper cheekteeth of a young domestic pig; some bunodont dentition, such as human teeth is simpler; others are more complex. 12) Calcar - In bats a process connected with the calcaneum (heel bone) and extending into the uropatagium near its edge, helping to support the uropatagium (the fold of skin that extends between the leg and tail). A keeled calcar is one with a definite flap of membrane posterior to the calcar extending beyond the general margin of the uropatagium. 13) Cancellous - Having a spongy or porous structure.

CHORDATA 16SCCZO3 01 14) Canine - Of, pertaining to, or designating the tooth next to the incisors in mammals. Of or pertaining to dogs or to the family Canidae. 15) Carnivore - An animal that preys on other animals; an animal that eats the flesh of other animals; especially any mammal of the Order Carnivora. 16) Cheek-teeth - Teeth behind the canines. 17) Conch (plural, conchs) - The external ear of a mammal; sometimes the spelling is concha (plural, conchae); the origin of both spellings is conch or konch, originally a bivalve shell of a marine mollusk. 18) Condylar (condyloid, articular) process. On a mandible, the process ending in the articular condyle. See "dentary".

SELF-ASSESSMENT QUESTIONS

Q1. Give an account of distinguishing characters and outline classification of mammals? Q2. Give the general characters and affinities of Prototheria? Q3. Give the affinities of Metathiria? Q4. Give the economic important of mammals? Q5 Write short note in: (a) Devlopment of tooth (b) Prototheria

TERMINAL QUESTION ANSWERS

1) The burrow of Rabbit is called: (a) Ware (b) Form (c) Barren (d) Barre 2) The tail in Rabbit serves as: (a) Balancing organs (b) Sensory organ (c) Decorative structure

CHORDATA 16SCCZO3 01 (d) Hearing aid 3) In mammal hind limbs are absent in: (a) Cetaceans (b) Rodents (c) Marsupials (d) Chiropterans 4) Teeth in mammals are: (a) Thecodont, homodont, diphyodont (b) Thecodont ,hetrodont,diphyodont (c) Acrodont, homodont, monophyodont (d) Acrodont, homodont, polyphyodont 5) Typical prototheria character is: (a) Presence of cloaca (b) 4 chambers heart (c) Tarsal squr in males (d) Segmented sternum 6) Metatherian teeth are more than: (a) 32 (b) 36 (c) 4 0 (d) 4.4 7) Milk dentition in mammals lack: (a) Molar (b) Premolars (c) Canines (d) Incisors

8) First teeth on maxillae: (a) Lower canines (b) Upper canines (c) Upper molar

CHORDATA 16SCCZO3 01 (d) Lower premolar 9) Baleen is present in: (a) Lizards (b) Frogs (c) Whales (d) Elephants 10) Largest mammalian suborder: (a) Logomorpha (b) Rodenta (c) Cetacea (d) Sireni

Answers

1(a) 2 (a) 3 (a) 4(b) 5 (c) 6 (d) 7(a) 8 (b) 9 (c) 10(b)

REFERENCES

1. Jordan E.L. and P.S. Verma 1995.Chordate Zoology and Elements of Animal Physiology.S.Chand and Co.New Delhi 2. Kotpal, R.L 2012.Vertebrata, Rastogi publication Merruth. 3. Nigam,H.C.1983.Zoology of chordates,Vishal publication,Jalandhar 4. Some figure and tax material are adopted from Wikipedia. 5. Some figure and tax material are adopted from Biozoom.

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